text
null | inputs
dict | prediction
null | prediction_agent
null | annotation
list | annotation_agent
null | multi_label
bool 1
class | explanation
null | id
stringlengths 1
5
| metadata
null | status
stringclasses 2
values | event_timestamp
null | metrics
null |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
null |
{
"abstract": " Recently, there is increasing interest and research on the interpretability\nof machine learning models, for example how they transform and internally\nrepresent EEG signals in Brain-Computer Interface (BCI) applications. This can\nhelp to understand the limits of the model and how it may be improved, in\naddition to possibly provide insight about the data itself. Schirrmeister et\nal. (2017) have recently reported promising results for EEG decoding with deep\nconvolutional neural networks (ConvNets) trained in an end-to-end manner and,\nwith a causal visualization approach, showed that they learn to use spectral\namplitude changes in the input. In this study, we investigate how ConvNets\nrepresent spectral features through the sequence of intermediate stages of the\nnetwork. We show higher sensitivity to EEG phase features at earlier stages and\nhigher sensitivity to EEG amplitude features at later stages. Intriguingly, we\nobserved a specialization of individual stages of the network to the classical\nEEG frequency bands alpha, beta, and high gamma. Furthermore, we find first\nevidence that particularly in the last convolutional layer, the network learns\nto detect more complex oscillatory patterns beyond spectral phase and\namplitude, reminiscent of the representation of complex visual features in\nlater layers of ConvNets in computer vision tasks. Our findings thus provide\ninsights into how ConvNets hierarchically represent spectral EEG features in\ntheir intermediate layers and suggest that ConvNets can exploit and might help\nto better understand the compositional structure of EEG time series.\n",
"title": "Hierarchical internal representation of spectral features in deep convolutional networks trained for EEG decoding"
}
| null | null | null | null | true | null |
4501
| null |
Default
| null | null |
null |
{
"abstract": " The coupled quasilinear Keller-Segel-Navier-Stokes system is considered under\nNeumann boundary conditions for $n$ and $c$ and no-slip boundary conditions for\n$u$ in three-dimensional bounded domains $\\Omega\\subseteq \\mathbb{R}^3$ with\nsmooth boundary, where $m>0,\\kappa\\in \\mathbb{R}$ are given constants, $\\phi\\in\nW^{1,\\infty}(\\Omega)$. If $ m> 2$, then for all reasonably regular initial\ndata, a corresponding initial-boundary value problem for $(KSNF)$ possesses a\nglobally defined weak solution.\n",
"title": "Global weak solutions in a three-dimensional Keller-Segel-Navier-Stokes system with nonlinear diffusion"
}
| null | null | null | null | true | null |
4502
| null |
Default
| null | null |
null |
{
"abstract": " Spectral clustering is one of the most popular methods for community\ndetection in graphs. A key step in spectral clustering algorithms is the eigen\ndecomposition of the $n{\\times}n$ graph Laplacian matrix to extract its $k$\nleading eigenvectors, where $k$ is the desired number of clusters among $n$\nobjects. This is prohibitively complex to implement for very large datasets.\nHowever, it has recently been shown that it is possible to bypass the eigen\ndecomposition by computing an approximate spectral embedding through graph\nfiltering of random signals. In this paper, we analyze the working of spectral\nclustering performed via graph filtering on the stochastic block model.\nSpecifically, we characterize the effects of sparsity, dimensionality and\nfilter approximation error on the consistency of the algorithm in recovering\nplanted clusters.\n",
"title": "On Consistency of Compressive Spectral Clustering"
}
| null | null | null | null | true | null |
4503
| null |
Default
| null | null |
null |
{
"abstract": " $\\textbf{Objective}$: To assess the validity of an automatic EEG arousal\ndetection algorithm using large patient samples and different heterogeneous\ndatabases\n$\\textbf{Methods}$: Automatic scorings were confronted with results from\nhuman expert scorers on a total of 2768 full-night PSG recordings obtained from\ntwo different databases. Of them, 472 recordings were obtained during clinical\nroutine at our sleep center and were subdivided into two subgroups of 220\n(HMC-S) and 252 (HMC-M) recordings each, attending to the procedure followed by\nthe clinical expert during the visual review (semi-automatic or purely manual,\nrespectively). In addition, 2296 recordings from the public SHHS-2 database\nwere evaluated against the respective manual expert scorings.\n$\\textbf{Results}$: Event-by-event epoch-based validation resulted in an\noverall Cohen kappa agreement K = 0.600 (HMC-S), 0.559 (HMC-M), and 0.573\n(SHHS-2). Estimated inter-scorer variability on the datasets was, respectively,\nK = 0.594, 0.561 and 0.543. Analyses of the corresponding Arousal Index scores\nshowed associated automatic-human repeatability indices ranging in 0.693-0.771\n(HMC-S), 0.646-0.791 (HMC-M), and 0.759-0.791 (SHHS-2).\n$\\textbf{Conclusions}$: Large-scale validation of our automatic EEG arousal\ndetector on different databases has shown robust performance and good\ngeneralization results comparable to the expected levels of human agreement.\nSpecial emphasis has been put on allowing reproducibility of the results and\nimplementation of our method has been made accessible online as open source\ncode\n",
"title": "Large-scale validation of an automatic EEG arousal detection algorithm using different heterogeneous databases"
}
| null | null |
[
"Quantitative Biology"
] | null | true | null |
4504
| null |
Validated
| null | null |
null |
{
"abstract": " We review the developments of the statistical physics of fracture and\nearthquake over the last four decades. We argue that major progress has been\nmade in this field and that the key concepts should now become integral part of\nthe (under-) graduate level text books in condensed matter physics. For arguing\nin favor of this, we compare the development (citations) with the same for some\nother related topics in condensed matter, for which Nobel prizes have already\nbeen awarded.\n",
"title": "Story of the Developments in Statistical Physics of Fracture, Breakdown \\& Earthquake: A Personal Account"
}
| null | null | null | null | true | null |
4505
| null |
Default
| null | null |
null |
{
"abstract": " We consider a localized approach in the well-established setting of\nreproducing kernel learning under random design. The input space $X$ is\npartitioned into local disjoint subsets $X_j$ ($j=1,...,m$) equipped with a\nlocal reproducing kernel $K_j$. It is then straightforward to define local KRR\nestimates. Our first main contribution is in showing that minimax optimal rates\nof convergence are preserved if the number $m$ of partitions grows sufficiently\nslowly with the sample size, under locally different degrees on smoothness\nassumptions on the regression function. As a byproduct, we show that low\nsmoothness on exceptional sets of small probability does not contribute,\nleading to a faster rate of convergence. Our second contribution lies in\nshowing that the partitioning approach for KRR can be efficiently combined with\nlocal Nyström subsampling, improving computational cost twofold. If the\nnumber of locally subsampled inputs grows sufficiently fast with the sample\nsize, minimax optimal rates of convergence are maintained.\n",
"title": "LocalNysation: A bottom up approach to efficient localized kernel regression"
}
| null | null | null | null | true | null |
4506
| null |
Default
| null | null |
null |
{
"abstract": " Directed graphs are widely used to model data flow and execution dependencies\nin streaming applications. This enables the utilization of graph partitioning\nalgorithms for the problem of parallelizing computation for multiprocessor\narchitectures. However due to resource restrictions, an acyclicity constraint\non the partition is necessary when mapping streaming applications to an\nembedded multiprocessor. Here, we contribute a multi-level algorithm for the\nacyclic graph partitioning problem. Based on this, we engineer an evolutionary\nalgorithm to further reduce communication cost, as well as to improve load\nbalancing and the scheduling makespan on embedded multiprocessor architectures.\n",
"title": "Evolutionary Acyclic Graph Partitioning"
}
| null | null | null | null | true | null |
4507
| null |
Default
| null | null |
null |
{
"abstract": " The wear-driven structural evolution of nanocrystalline Cu was simulated with\nmolecular dynamics under constant normal loads, followed by a quantitative\nanalysis. While the microstructure far away from the sliding contact remains\nunchanged, grain growth accompanied by partial dislocations and twin formation\nwas observed near the contact surface, with more rapid coarsening promoted by\nhigher applied normal loads. The structural evolution continues with increasing\nnumber of sliding cycles and eventually saturates to a stable distinct layer of\ncoarsened grains, separated from the finer matrix by a steep gradient in grain\nsize. The coarsening process is balanced by the rate of material removal when\nthe normal load is high enough. The observed structural evolution leads to an\nincrease in hardness and decrease in friction coefficient, which also saturate\nafter a number of sliding cycles. This work provides important mechanistic\nunderstanding of nanocrystalline wear, while also introducing a methodology for\natomistic simulations of cyclic wear damage under constant applied normal\nloads.\n",
"title": "Mechanisms of near-surface structural evolution in nanocrystalline materials during sliding contact"
}
| null | null | null | null | true | null |
4508
| null |
Default
| null | null |
null |
{
"abstract": " The aim of this paper is to present necessary and sufficient conditions for\ngeneralized Hölder's inequality on generalized Morrey spaces. We also\nobtain similar results on weak Morrey spaces and on generalized weak Morrey\nspaces. The necessary and sufficient conditions for the generalized\nHölder's inequality on these spaces are obtained through estimates for\ncharacteristic functions of balls in $\\mathbb{R}^d$.\n",
"title": "Generalized Hölder's inequality on Morrey spaces"
}
| null | null |
[
"Mathematics"
] | null | true | null |
4509
| null |
Validated
| null | null |
null |
{
"abstract": " This is (mostly) a survey article. We use an information about Galois\nproperties of points of small order on an abelian variety in order to describe\nits endomorphism algebra over an algebraic closure of the ground field. We\ndiscuss in detail applications to jacobians of cyclic covers of the projective\nline.\n",
"title": "Endomorphism Algebras of Abelian varieties with special reference to Superelliptic Jacobians"
}
| null | null |
[
"Mathematics"
] | null | true | null |
4510
| null |
Validated
| null | null |
null |
{
"abstract": " In this paper, we obtain bounds for the Mordell-Weil ranks over cyclotomic\nextensions of a wide range of abelian varieties defined over a number field $F$\nwhose primes above $p$ are totally ramified over $F/\\mathbb{Q}$. We assume that\nthe abelian varieties may have good non-ordinary reduction at those primes. Our\nwork is a generalization of \\cite{Kim}, in which the second author generalized\nPerrin-Riou's Iwasawa theory for elliptic curves over $\\mathbb{Q}$ with\nsupersingular reduction (\\cite{Perrin-Riou}) to elliptic curves defined over\nthe above-mentioned number field $F$. On top of non-ordinary reduction and the\nramification of the field $F$, we deal with the additional difficulty that the\ndimensions of the abelian varieties can be any number bigger than 1 which\ncauses a variety of issues. As a result, we obtain bounds for the ranks over\ncyclotomic extensions $\\mathbb{Q}(\\mu_{p^{\\max(M,N)+n}})$ of the Jacobian\nvarieties of {\\it ramified} hyperelliptic curves $y^{2p^M}=x^{3p^N}+ax^{p^N}+b$\namong others.\n",
"title": "Ranks of rational points of the Jacobian varieties of hyperelliptic curves"
}
| null | null | null | null | true | null |
4511
| null |
Default
| null | null |
null |
{
"abstract": " We have shown that in some region where the Euler integral of the first kind\ndiverges, the Euler formula defines a generalized function. The connected of\nthis generalized function with the Dirac delta function is found.\n",
"title": "A Generalized Function defined by the Euler first kind integral and its connection with the Dirac delta function"
}
| null | null | null | null | true | null |
4512
| null |
Default
| null | null |
null |
{
"abstract": " We report on the first experimental observation of graphene optical emission\ninduced by the intense THz pulse. P-doped CVD graphene with the initial Fermi\nenergy of about 200 meV was used, optical photons was detected in the\nwavelength range of 340-600 nm. Emission started when THz field amplitude\nexceeded 100 kV/cm. For THz fields from 200 to 300 kV/cm the temperature of\noptical radiation was constant, while the number of emitted photons increased\nseveral dozen times. This fact clearly indicates multiplication of\nelectron-hole pairs induced by an external field itself and not due to electron\nheating. The experimental data are in a good agreement with the theory of\nLandau-Zener interband transitions. It is shown theoretically that Landau-Zener\ntransitions are possible even in the case of heavily doped graphene because the\nstrong THz field removes quasiparticles from the region of interband\ntransitions during several femtoseconds, which cancels the Pauli blocking\neffect.\n",
"title": "Optical emission of graphene and electron-hole pair production induced by a strong THz field"
}
| null | null | null | null | true | null |
4513
| null |
Default
| null | null |
null |
{
"abstract": " Navigating safely in urban environments remains a challenging problem for\nautonomous vehicles. Occlusion and limited sensor range can pose significant\nchallenges to safely navigate among pedestrians and other vehicles in the\nenvironment. Enabling vehicles to quantify the risk posed by unseen regions\nallows them to anticipate future possibilities, resulting in increased safety\nand ride comfort. This paper proposes an algorithm that takes advantage of the\nknown road layouts to forecast, quantify, and aggregate risk associated with\nocclusions and limited sensor range. This allows us to make predictions of risk\ninduced by unobserved vehicles even in heavily occluded urban environments. The\nrisk can then be used either by a low-level planning algorithm to generate\nbetter trajectories, or by a high-level one to plan a better route. The\nproposed algorithm is evaluated on intersection layouts from real-world map\ndata with up to five other vehicles in the scene, and verified to reduce\ncollision rates by 4.8x comparing to a baseline method while improving driving\ncomfort.\n",
"title": "Occlusion-Aware Risk Assessment for Autonomous Driving in Urban Environments"
}
| null | null | null | null | true | null |
4514
| null |
Default
| null | null |
null |
{
"abstract": " When magnetic field is applied to metals and semimetals quantum oscillations\nappear as individual Landau levels cross the Fermi level. Quantum oscillations\ngenerally do not occur in superconductors (SC) because magnetic field is either\nexpelled from the sample interior or, if strong enough, drives the material\ninto the normal state. In addition, elementary excitations of a superconductor\n-- Bogoliubov quasiparticles -- do not carry a well defined electric charge and\ntherefore do not couple in a simple way to the applied magnetic field. We\npredict here that in Weyl superconductors certain types of elastic strain have\nthe ability to induce chiral pseudo-magnetic field which can reorganize the\nelectronic states into Dirac-Landau levels with linear band crossings at low\nenergy. The resulting quantum oscillations in the quasiparticle density of\nstates and thermal conductivity can be experimentally observed under a bending\ndeformation of a thin film Weyl SC and provide new insights into this\nfascinating family of materials.\n",
"title": "Quantum oscillations and Dirac-Landau levels in Weyl superconductors"
}
| null | null | null | null | true | null |
4515
| null |
Default
| null | null |
null |
{
"abstract": " The emergence and development of cancer is a consequence of the accumulation\nover time of genomic mutations involving a specific set of genes, which\nprovides the cancer clones with a functional selective advantage. In this work,\nwe model the order of accumulation of such mutations during the progression,\nwhich eventually leads to the disease, by means of probabilistic graphic\nmodels, i.e., Bayesian Networks (BNs). We investigate how to perform the task\nof learning the structure of such BNs, according to experimental evidence,\nadopting a global optimization meta-heuristics. In particular, in this work we\nrely on Genetic Algorithms, and to strongly reduce the execution time of the\ninference -- which can also involve multiple repetitions to collect\nstatistically significant assessments of the data -- we distribute the\ncalculations using both multi-threading and a multi-node architecture. The\nresults show that our approach is characterized by good accuracy and\nspecificity; we also demonstrate its feasibility, thanks to a 84x reduction of\nthe overall execution time with respect to a traditional sequential\nimplementation.\n",
"title": "Parallel Implementation of Efficient Search Schemes for the Inference of Cancer Progression Models"
}
| null | null | null | null | true | null |
4516
| null |
Default
| null | null |
null |
{
"abstract": " In this paper we correct an inaccuracy that appears in the proof of Theorem\n1. in Czerwik's article \"Contraction mappings in $b$-metric spaces.\", Acta\nMath. Inform. Univ. Ostraviensis, 1:5--11, 1993.\n",
"title": "A note on the paper \"Contraction mappings in $b$-metric spaces\" by Czerwik"
}
| null | null | null | null | true | null |
4517
| null |
Default
| null | null |
null |
{
"abstract": " In the present work, we aim at taking a step towards the spectral stability\nanalysis of Peregrine solitons, i.e., wave structures that are used to emulate\nextreme wave events. Given the space-time localized nature of Peregrine\nsolitons, this is a priori a non-trivial task. Our main tool in this effort\nwill be the study of the spectral stability of the periodic generalization of\nthe Peregrine soliton in the evolution variable, namely the Kuznetsov--Ma\nbreather. Given the periodic structure of the latter, we compute the\ncorresponding Floquet multipliers, and examine them in the limit where the\nperiod of the orbit tends to infinity. This way, we extrapolate towards the\nstability of the limiting structure, namely the Peregrine soliton. We find that\nmultiple unstable modes of the background are enhanced, yet no additional\nunstable eigenmodes arise as the Peregrine limit is approached. We explore the\ninstability evolution also in direct numerical simulations.\n",
"title": "Floquet Analysis of Kuznetsov--Ma breathers: A Path Towards Spectral Stability of Rogue Waves"
}
| null | null |
[
"Physics"
] | null | true | null |
4518
| null |
Validated
| null | null |
null |
{
"abstract": " We investigate a dynamically adapting tuning scheme for microtonal tuning of\nmusical instruments, allowing the performer to play music in just intonation in\nany key. Unlike other methods, which are based on a procedural analysis of the\nchordal structure, the tuning scheme continually solves a system of linear\nequations without making explicit decisions. In complex situations, where not\nall intervals of a chord can be tuned according to just frequency ratios, the\nmethod automatically yields a tempered compromise. We outline the\nimplementation of the algorithm in an open-source software project that we have\nprovided in order to demonstrate the feasibility of the tuning method.\n",
"title": "Playing Music in Just Intonation - A Dynamically Adapting Tuning Scheme"
}
| null | null |
[
"Physics"
] | null | true | null |
4519
| null |
Validated
| null | null |
null |
{
"abstract": " We provide an analytic propagator for non-Hermitian dimers showing linear\ngain or losses in the quantum regime. In particular, we focus on experimentally\nfeasible realizations of the $\\mathcal{PT}$-symmetric dimer and provide their\nmean photon number and second order two-point correlation. We study the\npropagation of vacuum, single photon spatially-separable, and two-photon\nspatially-entangled states. We show that each configuration produces a\nparticular signature that might signal their possible uses as photon switches,\nsemi-classical intensity-tunable sources, or spatially entangled sources to\nmention a few possible applications.\n",
"title": "Photon propagation through linearly active dimers"
}
| null | null |
[
"Physics"
] | null | true | null |
4520
| null |
Validated
| null | null |
null |
{
"abstract": " We propose a novel deep learning architecture for regressing disparity from a\nrectified pair of stereo images. We leverage knowledge of the problem's\ngeometry to form a cost volume using deep feature representations. We learn to\nincorporate contextual information using 3-D convolutions over this volume.\nDisparity values are regressed from the cost volume using a proposed\ndifferentiable soft argmin operation, which allows us to train our method\nend-to-end to sub-pixel accuracy without any additional post-processing or\nregularization. We evaluate our method on the Scene Flow and KITTI datasets and\non KITTI we set a new state-of-the-art benchmark, while being significantly\nfaster than competing approaches.\n",
"title": "End-to-End Learning of Geometry and Context for Deep Stereo Regression"
}
| null | null | null | null | true | null |
4521
| null |
Default
| null | null |
null |
{
"abstract": " Recently, distributed processing of large dynamic graphs has become very\npopular, especially in certain domains such as social network analysis, Web\ngraph analysis and spatial network analysis. In this context, many\ndistributed/parallel graph processing systems have been proposed, such as\nPregel, GraphLab, and Trinity. These systems can be divided into two\ncategories: (1) vertex-centric and (2) block-centric approaches. In\nvertex-centric approaches, each vertex corresponds to a process, and message\nare exchanged among vertices. In block-centric approaches, the unit of\ncomputation is a block, a connected subgraph of the graph, and message\nexchanges occur among blocks. In this paper, we are considering the issues of\nscale and dynamism in the case of block-centric approaches. We present bladyg,\na block-centric framework that addresses the issue of dynamism in large-scale\ngraphs. We present an implementation of BLADYG on top of akka framework. We\nexperimentally evaluate the performance of the proposed framework.\n",
"title": "BLADYG: A Graph Processing Framework for Large Dynamic Graphs"
}
| null | null | null | null | true | null |
4522
| null |
Default
| null | null |
null |
{
"abstract": " Variational inference methods often focus on the problem of efficient model\noptimization, with little emphasis on the choice of the approximating\nposterior. In this paper, we review and implement the various methods that\nenable us to develop a rich family of approximating posteriors. We show that\none particular method employing transformations on distributions results in\ndeveloping very rich and complex posterior approximation. We analyze its\nperformance on the MNIST dataset by implementing with a Variational Autoencoder\nand demonstrate its effectiveness in learning better posterior distributions.\n",
"title": "Variational Inference via Transformations on Distributions"
}
| null | null | null | null | true | null |
4523
| null |
Default
| null | null |
null |
{
"abstract": " The discrete cosine transform (DCT) is a widely-used and important signal\nprocessing tool employed in a plethora of applications. Typical fast algorithms\nfor nearly-exact computation of DCT require floating point arithmetic, are\nmultiplier intensive, and accumulate round-off errors. Recently proposed fast\nalgorithm arithmetic cosine transform (ACT) calculates the DCT exactly using\nonly additions and integer constant multiplications, with very low area\ncomplexity, for null mean input sequences. The ACT can also be computed\nnon-exactly for any input sequence, with low area complexity and low power\nconsumption, utilizing the novel architecture described. However, as a\ntrade-off, the ACT algorithm requires 10 non-uniformly sampled data points to\ncalculate the 8-point DCT. This requirement can easily be satisfied for\napplications dealing with spatial signals such as image sensors and biomedical\nsensor arrays, by placing sensor elements in a non-uniform grid. In this work,\na hardware architecture for the computation of the null mean ACT is proposed,\nfollowed by a novel architectures that extend the ACT for non-null mean\nsignals. All circuits are physically implemented and tested using the Xilinx\nXC6VLX240T FPGA device and synthesized for 45 nm TSMC standard-cell library for\nperformance assessment.\n",
"title": "VLSI Computational Architectures for the Arithmetic Cosine Transform"
}
| null | null | null | null | true | null |
4524
| null |
Default
| null | null |
null |
{
"abstract": " We propose a swarm-based optimization algorithm inspired by air currents of a\ntornado. Two main air currents - spiral and updraft - are mimicked. Spiral\nmotion is designed for exploration of new search areas and updraft movements is\ndeployed for exploitation of a promising candidate solution. Assignment of just\none search direction to each particle at each iteration, leads to low\ncomputational complexity of the proposed algorithm respect to the conventional\nalgorithms. Regardless of the step size parameters, the only parameter of the\nproposed algorithm, called tornado diameter, can be efficiently adjusted by\nrandomization. Numerical results over six different benchmark cost functions\nindicate comparable and, in some cases, better performance of the proposed\nalgorithm respect to some other metaheuristics.\n",
"title": "Simulated Tornado Optimization"
}
| null | null | null | null | true | null |
4525
| null |
Default
| null | null |
null |
{
"abstract": " In this paper, we consider a backward in time problem for Ginzburg-Landau\nequation in multidimensional domain associated with some random data. The\nproblem is ill-posed in the sense of Hadamard. To regularize the instable\nsolution, we develop a new regularized method combined with statistical\napproach to solve this problem. We prove a upper bound, on the rate of\nconvergence of the mean integrated squared error in $L^2 $ norm and $H^1$ norm.\n",
"title": "On a backward problem for multidimensional Ginzburg-Landau equation with random data"
}
| null | null | null | null | true | null |
4526
| null |
Default
| null | null |
null |
{
"abstract": " In this brief review we discuss the transient processes in solids under\nirradiation with femtosecond X-ray free-electron-laser (FEL) pulses and\nswift-heavy ions (SHI). Both kinds of irradiation produce highly excited\nelectrons in a target on extremely short timescales. Transfer of the excess\nelectronic energy into the lattice may lead to observable target modifications\nsuch as phase transitions and damage formation. Transient kinetics of material\nexcitation and relaxation under FEL or SHI irradiation are comparatively\ndiscussed. The same origin for the electronic and atomic relaxation in both\ncases is demonstrated. Differences in these kinetics introduced by the\ngeometrical effects ({\\mu}m-size of a laser spot vs nm-size of an ion track)\nand initial irradiation (photoabsorption vs an ion impact) are analyzed. The\nbasic mechanisms of electron transport and electron-lattice coupling are\naddressed. Appropriate models and their limitations are presented.\nPossibilities of thermal and nonthermal melting of materials under FEL and SHI\nirradiation are discussed.\n",
"title": "Electronic and atomic kinetics in solids irradiated with free-electron lasers or swift-heavy ions"
}
| null | null | null | null | true | null |
4527
| null |
Default
| null | null |
null |
{
"abstract": " The galaxy data provided by COSMOS survey for 1 by 1 degree field of sky are\nanalysed by methods of complex networks. Three galaxy samples (slices) with\nredshifts ranging within intervals 0.88-0.91, 0.91-0.94 and 0.94-0.97 are\nstudied as two-dimensional projections for the spatial distributions of\ngalaxies. We construct networks and calculate network measures for each sample,\nin order to analyse the network similarity of different samples, distinguish\nvarious topological environments, and find associations between galaxy\nproperties (colour index and stellar mass) and their topological environments.\nResults indicate a high level of similarity between geometry and topology for\ndifferent galaxy samples and no clear evidence of evolutionary trends in\nnetwork measures. The distribution of local clustering coefficient C manifests\nthree modes which allow for discrimination between stand-alone singlets and\ndumbbells (0 <= C <= 0.1), intermediately (0 < C < 0.9) and clique (0.9 <= C <=\n1) like galaxies. Analysing astrophysical properties of galaxies (colour index\nand stellar masses), we show that distributions are similar in all slices,\nhowever weak evolutionary trends can also be seen across redshift slices. To\nspecify different topological environments we have extracted selections of\ngalaxies from each sample according to different modes of C distribution. We\nhave found statistically significant associations between evolutionary\nparameters of galaxies and selections of C: the distribution of stellar mass\nfor galaxies with interim C differ from the corresponding distributions for\nstand-alone and clique galaxies, and this difference holds for all redshift\nslices. The colour index realises somewhat different behaviour.\n",
"title": "Network analysis of the COSMOS galaxy field"
}
| null | null |
[
"Physics"
] | null | true | null |
4528
| null |
Validated
| null | null |
null |
{
"abstract": " Digital advances have transformed the face of automatic music generation\nsince its beginnings at the dawn of computing. Despite the many breakthroughs,\nissues such as the musical tasks targeted by different machines and the degree\nto which they succeed remain open questions. We present a functional taxonomy\nfor music generation systems with reference to existing systems. The taxonomy\norganizes systems according to the purposes for which they were designed. It\nalso reveals the inter-relatedness amongst the systems. This design-centered\napproach contrasts with predominant methods-based surveys and facilitates the\nidentification of grand challenges to set the stage for new breakthroughs.\n",
"title": "A Functional Taxonomy of Music Generation Systems"
}
| null | null | null | null | true | null |
4529
| null |
Default
| null | null |
null |
{
"abstract": " Singular actions on C*-algebras are automorphic group actions on C*-algebras,\nwhere the group need not be locally compact, or the action need not be strongly\ncontinuous. We study the covariant representation theory of such actions. In\nthe usual case of strongly continuous actions of locally compact groups on\nC*-algebras, this is done via crossed products, but this approach is not\navailable for singular C*-actions (this was our path in a previous paper). The\nliterature regarding covariant representations for singular actions is already\nlarge and scattered, and in need of some consolidation. We collect in this\nsurvey a range of results in this field, mostly known. We improve some proofs\nand elucidate some interconnections. These include existence theorems by\nBorchers and Halpern, Arveson spectra, the Borchers-Arveson theorem, standard\nrepresentations and Stinespring dilations as well as ground states, KMS states\nand ergodic states and the spatial structure of their GNS representations.\n",
"title": "Covariant representations for singular actions on C*-algebras"
}
| null | null | null | null | true | null |
4530
| null |
Default
| null | null |
null |
{
"abstract": " General purpose correct-by-construction synthesis methods are limited to\nsystems with low dimensionality or simple specifications. In this work we\nconsider highly symmetrical counting problems and exploit the symmetry to\nsynthesize provably correct controllers for systems with tens of thousands of\nstates. The key ingredients of the solution are an aggregate abstraction\nprocedure for mildly heterogeneous systems and a formulation of counting\nconstraints as linear inequalities.\n",
"title": "Control Synthesis for Permutation-Symmetric High-Dimensional Systems With Counting Constraints"
}
| null | null | null | null | true | null |
4531
| null |
Default
| null | null |
null |
{
"abstract": " In this study, explicit differential equations representing commutative pairs\nof some well-known second-order linear time-varying systems have been derived.\nThe commutativity of these systems are investigated by considering 30\nsecond-order linear differential equations with variable coefficients. It is\nshown that the system modeled by each one of these equations has a commutative\npair with (or without) some conditions or not. There appear special cases such\nthat both, only one or neither of the original system and its commutative pair\nhas explicit analytic solution. Some benefits of commutativity have already\nbeen mentioned in the literature but a new application for in cryptology for\nobscuring transmitted signals in telecommunication is illustrated in this\npaper.\n",
"title": "Commutativity and Commutative Pairs of Some Differential Equations"
}
| null | null | null | null | true | null |
4532
| null |
Default
| null | null |
null |
{
"abstract": " More than 10^43 positrons annihilate every second in the centre of our Galaxy\nyet, despite four decades of observations, their origin is still unknown. Many\ncandidates have been proposed, such as supernovae and low mass X-ray binaries.\nHowever, these models are difficult to reconcile with the distribution of\npositrons, which are highly concentrated in the Galactic bulge, and therefore\nrequire specific propagation of the positrons through the interstellar medium.\nAlternative sources include dark matter decay, or the supermassive black hole,\nboth of which would have a naturally high bulge-to-disc ratio.\nThe chief difficulty in reconciling models with the observations is the\nintrinsically poor angular resolution of gamma-ray observations, which cannot\nresolve point sources. Essentially all of the positrons annihilate via the\nformation of positronium. This gives rise to the possibility of observing\nrecombination lines of positronium emitted before the atom annihilates. These\nemission lines would be in the UV and the NIR, giving an increase in angular\nresolution of a factor of 10^4 compared to gamma ray observations, and allowing\nthe discrimination between point sources and truly diffuse emission.\nAnalogously to the formation of positronium, it is possible to form atoms of\ntrue muonium and true tauonium. Since muons and tauons are intrinsically\nunstable, the formation of such leptonium atoms will be localised to their\nplaces of origin. Thus observations of true muonium or true tauonium can\nprovide another way to distinguish between truly diffuse sources such as dark\nmatter decay, and an unresolved distribution of point sources.\n",
"title": "Astrophysical signatures of leptonium"
}
| null | null | null | null | true | null |
4533
| null |
Default
| null | null |
null |
{
"abstract": " Sampling technique has become one of the recent research focuses in the\ngraph-related fields. Most of the existing graph sampling algorithms tend to\nsample the high degree or low degree nodes in the complex networks because of\nthe characteristic of scale-free. Scale-free means that degrees of different\nnodes are subject to a power law distribution. So, there is a significant\ndifference in the degrees between the overall sampling nodes. In this paper, we\npropose an idea of approximate degree distribution and devise a stratified\nstrategy using it in the complex networks. We also develop two graph sampling\nalgorithms combining the node selection method with the stratified strategy.\nThe experimental results show that our sampling algorithms preserve several\nproperties of different graphs and behave more accurately than other\nalgorithms. Further, we prove the proposed algorithms are superior to the\noff-the-shelf algorithms in terms of the unbiasedness of the degrees and more\nefficient than state-of-the-art FFS and ES-i algorithms.\n",
"title": "Enhancing Stratified Graph Sampling Algorithms based on Approximate Degree Distribution"
}
| null | null | null | null | true | null |
4534
| null |
Default
| null | null |
null |
{
"abstract": " Friendship and antipathy exist in concert with one another in real social\nnetworks. Despite the role they play in social interactions, antagonistic ties\nare poorly understood and infrequently measured. One important theory of\nnegative ties that has received relatively little empirical evaluation is\nbalance theory, the codification of the adage `the enemy of my enemy is my\nfriend' and similar sayings. Unbalanced triangles are those with an odd number\nof negative ties, and the theory posits that such triangles are rare. To test\nfor balance, previous works have utilized a permutation test on the edge signs.\nThe flaw in this method, however, is that it assumes that negative and positive\nedges are interchangeable. In reality, they could not be more different. Here,\nwe propose a novel test of balance that accounts for this discrepancy and show\nthat our test is more accurate at detecting balance. Along the way, we prove\nasymptotic normality of the test statistic under our null model, which is of\nindependent interest. Our case study is a novel dataset of signed networks we\ncollected from 32 isolated, rural villages in Honduras. Contrary to previous\nresults, we find that there is only marginal evidence for balance in social tie\nformation in this setting.\n",
"title": "Testing for Balance in Social Networks"
}
| null | null | null | null | true | null |
4535
| null |
Default
| null | null |
null |
{
"abstract": " We review the recurrence intervals as a function of ground motion amplitude\nat several terrestrial locations, and make the first interplanetary comparison\nwith measurements on the Moon, Mars, Venus and Titan. This empirical approach\ngives an intuitive guide to the relative seismicity of these locations, without\ninvoking interior models and specific sources: for example a Venera-14\nobservation of possible ground motion indicates a microseismic environment\nmid-way between noisy and quiet terrestrial locations; quiet terrestrial\nregions see a peak velocity amplitude in mm/s roughly equal to 0.4*N(-0.7),\nwhere N is the number of events observed per year. The Apollo data show signals\nfor a given recurrence rate are typically about 10,000 times smaller in\namplitude than a quiet site on Earth, while Viking data masked for low-wind\nperiods appears comparable with a quiet terrestrial site. Recurrence rate plots\nfrom in-situ measurements provide a convenient guide to expectations for\nseismic instrumentation on future planetary missions : while small geophones\ncan discriminate terrestrial activity rates, observations with guidance\naccelerometers are typically too insensitive to provide meaningful constraints\nunless operated for long periods.\n",
"title": "Empirical Recurrence Rates for Seismic Signals on Planetary Surfaces"
}
| null | null | null | null | true | null |
4536
| null |
Default
| null | null |
null |
{
"abstract": " Modern and future particle accelerators employ increasingly higher intensity\nand brighter beams of charged particles and become operationally limited by\ncoherent beam instabilities. Usual methods to control the instabilities, such\nas octupole magnets, beam feedback dampers and use of chromatic effects, become\nless effective and insufficient. We show that, in contrast, Lorentz forces of a\nlow-energy, a magnetically stabilized electron beam, or \"electron lens\", easily\nintroduces transverse nonlinear focusing sufficient for Landau damping of\ntransverse beam instabilities in accelerators. It is also important that,\nunlike other nonlinear elements, the electron lens provides the frequency\nspread mainly at the beam core, thus allowing much higher frequency spread\nwithout lifetime degradation. For the parameters of the Future Circular\nCollider, a single conventional electron lens a few meters long would provide\nstabilization superior to tens of thousands of superconducting octupole\nmagnets.\n",
"title": "Landau Damping of Beam Instabilities by Electron Lenses"
}
| null | null | null | null | true | null |
4537
| null |
Default
| null | null |
null |
{
"abstract": " In this paper, some algebraic and combinatorial characterizations of the\nspanning simplicial complex $\\Delta_s(\\mathcal{J}_{n,m})$ of the Jahangir's\ngraph $\\mathcal{J}_{n,m}$ are explored. We show that\n$\\Delta_s(\\mathcal{J}_{n,m})$ is pure, present the formula for $f$-vectors\nassociated to it and hence deduce a recipe for computing the Hilbert series of\nthe Face ring $k[\\Delta_s(\\mathcal{J}_{n,m})]$. Finaly, we show that the face\nring of $\\Delta_s(\\mathcal{J}_{n,m})$ is Cohen-Macaulay and give some open\nscopes of the current work.\n",
"title": "On Algebraic Characterization of SSC of the Jahangir's Graph $\\mathcal{J}_{n,m}$"
}
| null | null | null | null | true | null |
4538
| null |
Default
| null | null |
null |
{
"abstract": " In this paper we show how the stochastic heavy ball method (SHB) -- a popular\nmethod for solving stochastic convex and non-convex optimization problems\n--operates as a randomized gossip algorithm. In particular, we focus on two\nspecial cases of SHB: the Randomized Kaczmarz method with momentum and its\nblock variant. Building upon a recent framework for the design and analysis of\nrandomized gossip algorithms, [Loizou Richtarik, 2016] we interpret the\ndistributed nature of the proposed methods. We present novel protocols for\nsolving the average consensus problem where in each step all nodes of the\nnetwork update their values but only a subset of them exchange their private\nvalues. Numerical experiments on popular wireless sensor networks showing the\nbenefits of our protocols are also presented.\n",
"title": "Accelerated Gossip via Stochastic Heavy Ball Method"
}
| null | null | null | null | true | null |
4539
| null |
Default
| null | null |
null |
{
"abstract": " Attention-based models have recently shown great performance on a range of\ntasks, such as speech recognition, machine translation, and image captioning\ndue to their ability to summarize relevant information that expands through the\nentire length of an input sequence. In this paper, we analyze the usage of\nattention mechanisms to the problem of sequence summarization in our end-to-end\ntext-dependent speaker recognition system. We explore different topologies and\ntheir variants of the attention layer, and compare different pooling methods on\nthe attention weights. Ultimately, we show that attention-based models can\nimproves the Equal Error Rate (EER) of our speaker verification system by\nrelatively 14% compared to our non-attention LSTM baseline model.\n",
"title": "Attention-Based Models for Text-Dependent Speaker Verification"
}
| null | null |
[
"Computer Science",
"Statistics"
] | null | true | null |
4540
| null |
Validated
| null | null |
null |
{
"abstract": " Similarity and metric learning provides a principled approach to construct a\ntask-specific similarity from weakly supervised data. However, these methods\nare subject to the curse of dimensionality: as the number of features grows\nlarge, poor generalization is to be expected and training becomes intractable\ndue to high computational and memory costs. In this paper, we propose a\nsimilarity learning method that can efficiently deal with high-dimensional\nsparse data. This is achieved through a parameterization of similarity\nfunctions by convex combinations of sparse rank-one matrices, together with the\nuse of a greedy approximate Frank-Wolfe algorithm which provides an efficient\nway to control the number of active features. We show that the convergence rate\nof the algorithm, as well as its time and memory complexity, are independent of\nthe data dimension. We further provide a theoretical justification of our\nmodeling choices through an analysis of the generalization error, which depends\nlogarithmically on the sparsity of the solution rather than on the number of\nfeatures. Our experiments on datasets with up to one million features\ndemonstrate the ability of our approach to generalize well despite the high\ndimensionality as well as its superiority compared to several competing\nmethods.\n",
"title": "Escaping the Curse of Dimensionality in Similarity Learning: Efficient Frank-Wolfe Algorithm and Generalization Bounds"
}
| null | null | null | null | true | null |
4541
| null |
Default
| null | null |
null |
{
"abstract": " Skills learned through (deep) reinforcement learning often generalizes poorly\nacross domains and re-training is necessary when presented with a new task. We\npresent a framework that combines techniques in \\textit{formal methods} with\n\\textit{reinforcement learning} (RL). The methods we provide allows for\nconvenient specification of tasks with logical expressions, learns hierarchical\npolicies (meta-controller and low-level controllers) with well-defined\nintrinsic rewards, and construct new skills from existing ones with little to\nno additional exploration. We evaluate the proposed methods in a simple grid\nworld simulation as well as a more complicated kitchen environment in AI2Thor\n",
"title": "Automata-Guided Hierarchical Reinforcement Learning for Skill Composition"
}
| null | null | null | null | true | null |
4542
| null |
Default
| null | null |
null |
{
"abstract": " We analyze an open many-body system that is strongly coupled at its\nboundaries to interacting quantum baths. We show that the two-body interactions\ninside the baths induce emergent phenomena in the spin transport. The system\nand baths are modeled as independent spin chains resulting in a global\nnon-homogeneous XXZ model. The evolution of the system-bath state is simulated\nusing matrix-product-states methods. We present two phase transitions induced\nby bath interactions. For weak bath interactions we observe ballistic and\ninsulating phases. However, for strong bath interactions a diffusive phase\nemerges with a distinct power-law decay of the time-dependent spin current\n$Q\\propto t^{-\\alpha}$. Furthermore, we investigate long-lasting current\noscillations arising from the non-Markovian dynamics in the homogeneous case,\nand find a sharp change in their frequency scaling coinciding with the triple\npoint of the phase diagram.\n",
"title": "Emergent transport in a many-body open system driven by interacting quantum baths"
}
| null | null | null | null | true | null |
4543
| null |
Default
| null | null |
null |
{
"abstract": " In this paper, the effect of transmitter beam size on the performance of free\nspace optical (FSO) communication has been determined experimentally.\nIrradiance profile for varying turbulence strength is obtained using optical\nturbulence generating (OTG) chamber inside laboratory environment. Based on the\nresults, an optimum beam size is investigated using the semi-analytical method.\nMoreover, the combined effects of atmospheric scintillation and beam wander\ninduced pointing errors are considered in order to determine the optimum beam\nsize that minimizes the bit error rate (BER) of the system for a fixed\ntransmitter power and link length. The results show that the optimum beam size\nincreases with the increase in zenith angle but has negligible effect with the\nincrease in fade threshold level at low turbulence levels and has a marginal\neffect at high turbulence levels. Finally, the obtained outcome is useful for\nFSO system design and BER performance analysis.\n",
"title": "Experimental Investigation of Optimum Beam Size for FSO Uplink"
}
| null | null | null | null | true | null |
4544
| null |
Default
| null | null |
null |
{
"abstract": " Mars' surface bears the imprint of valley networks formed billions of years\nago and their relicts can still be observed today. However, whether these\nnetworks were formed by groundwater sapping, ice melt, or fluvial runoff has\nbeen continuously debated. These different scenarios have profoundly different\nimplications for Mars' climatic history, and thus for its habitability in the\ndistant past. Recent studies on Earth revealed that channel networks in arid\nlandscapes with more surface runoff branch at narrower angles, while in humid\nenvironments with more groundwater flow, branching angles are much wider. We\nfind that valley networks on Mars generally tend to branch at narrow angles\nsimilar to those found in arid landscapes on Earth. This result supports the\ninference that Mars once had an active hydrologic cycle and that Mars' valley\nnetworks were formed primarily by overland flow erosion with groundwater\nseepage playing only a minor role.\n",
"title": "The role of surface water in the geometry of Mars' valley networks and its climatic implications"
}
| null | null | null | null | true | null |
4545
| null |
Default
| null | null |
null |
{
"abstract": " This paper proposes an image dehazing model built with a convolutional neural\nnetwork (CNN), called All-in-One Dehazing Network (AOD-Net). It is designed\nbased on a re-formulated atmospheric scattering model. Instead of estimating\nthe transmission matrix and the atmospheric light separately as most previous\nmodels did, AOD-Net directly generates the clean image through a light-weight\nCNN. Such a novel end-to-end design makes it easy to embed AOD-Net into other\ndeep models, e.g., Faster R-CNN, for improving high-level task performance on\nhazy images. Experimental results on both synthesized and natural hazy image\ndatasets demonstrate our superior performance than the state-of-the-art in\nterms of PSNR, SSIM and the subjective visual quality. Furthermore, when\nconcatenating AOD-Net with Faster R-CNN and training the joint pipeline from\nend to end, we witness a large improvement of the object detection performance\non hazy images.\n",
"title": "An All-in-One Network for Dehazing and Beyond"
}
| null | null |
[
"Computer Science"
] | null | true | null |
4546
| null |
Validated
| null | null |
null |
{
"abstract": " In the spirit of searching for Gd-based, frustrated, rare earth magnets, we\nhave found antiferomagnetism (AF) in GdPtPb which crystallizes in the\nZrNiAl-type structure that has a distorted Kagomé lattice of Gd-triangles.\nSingle crystals were grown and investigated using structural, magnetic,\ntransport and thermodynamic measurements. GdPtPb orders antiferromagnetically\nat 15.5 K arguably with a planar, non-collinear structure. The high temperature\nmagnetic susceptibility data reveal an \"anti-frustration\" behavior having a\nfrustration parameter, $|f|$ = $|\\Theta|$/ $T_N$ = 0.25, which can be explained\nby mean field theory (MFT) within a two sub-lattice model. Study of the\nmagnetic phase diagram down to $T$ = 1.8 K reveals a change of magnetic\nstructure through a metamagnetic transition at around 20 kOe and the\ndisappearance of the AF ordering near 140 kOe. In total, our work indicates\nthat, GdPtPb can serve as an example of a planar, non collinear, AF with a\ndistorted Kagomé magnetic sub-lattice.\n",
"title": "GdPtPb: A non collinear antiferromagnet with distorted Kagomé lattice"
}
| null | null |
[
"Physics"
] | null | true | null |
4547
| null |
Validated
| null | null |
null |
{
"abstract": " In the note, all indecomposable canonical forms of linear systems with\ndimension less than or equal to $4$ are determined based on Belitskii's\nalgorithm. As an application, an effective way to calculate dimensions of\nequivalence classes of linear systems is given by using Belitskii's canonical\nforms.\n",
"title": "Belitskii's canonical forms of linear dynamical systems"
}
| null | null |
[
"Mathematics"
] | null | true | null |
4548
| null |
Validated
| null | null |
null |
{
"abstract": " Let $(M,g)$ be a compact manifold and let $-\\Delta \\phi_k = \\lambda_k \\phi_k$\nbe the sequence of Laplacian eigenfunctions. We present a curious new\nphenomenon which, so far, we only managed to understand in a few highly\nspecialized cases: the family of functions $f_N:M \\rightarrow \\mathbb{R}_{\\geq\n0}$ $$ f_N(x) = \\sum_{k \\leq N}{ \\frac{1}{\\sqrt{\\lambda_k}}\n\\frac{|\\phi_k(x)|}{\\|\\phi_k\\|_{L^{\\infty}(M)}}}$$ seems strangely suited for\nthe detection of anomalous points on the manifold. It may be heuristically\ninterpreted as the sum over distances to the nearest nodal line and potentially\nhints at a new phenomenon in spectral geometry. We give rigorous statements on\nthe unit square $[0,1]^2$ (where minima localize in $\\mathbb{Q}^2$) and on\nPaley graphs (where $f_N$ recovers the geometry of quadratic residues of the\nunderlying finite field $\\mathbb{F}_p$). Numerical examples show that the\nphenomenon seems to arise on fairly generic manifolds.\n",
"title": "The Geometry of Nodal Sets and Outlier Detection"
}
| null | null | null | null | true | null |
4549
| null |
Default
| null | null |
null |
{
"abstract": " Multimodal clustering is an unsupervised technique for mining interesting\npatterns in $n$-adic binary relations or $n$-mode networks. Among different\ntypes of such generalized patterns one can find biclusters and formal concepts\n(maximal bicliques) for 2-mode case, triclusters and triconcepts for 3-mode\ncase, closed $n$-sets for $n$-mode case, etc. Object-attribute biclustering\n(OA-biclustering) for mining large binary datatables (formal contexts or 2-mode\nnetworks) arose by the end of the last decade due to intractability of\ncomputation problems related to formal concepts; this type of patterns was\nproposed as a meaningful and scalable approximation of formal concepts. In this\npaper, our aim is to present recent advance in OA-biclustering and its\nextensions to mining multi-mode communities in SNA setting. We also discuss\nconnection between clustering coefficients known in SNA community for 1-mode\nand 2-mode networks and OA-bicluster density, the main quality measure of an\nOA-bicluster. Our experiments with 2-, 3-, and 4-mode large real-world networks\nshow that this type of patterns is suitable for community detection in\nmulti-mode cases within reasonable time even though the number of corresponding\n$n$-cliques is still unknown due to computation difficulties. An interpretation\nof OA-biclusters for 1-mode networks is provided as well.\n",
"title": "Multimodal Clustering for Community Detection"
}
| null | null | null | null | true | null |
4550
| null |
Default
| null | null |
null |
{
"abstract": " In this paper we solve the problem of the identification of a coefficient\nwhich appears in the model of a distributed system with persistent memory\nencountered in linear viscoelasticity (and in diffusion processes with memory).\nThe additional data used in the identification are subsumed in the input output\nmap from the deformation to the traction on the boundary. We extend a dynamical\napproach to identification introduced by Belishev in the case of purely elastic\n(memoryless) bodies and based on a special equation due to Blagoveshchenskii.\nSo, in particular, we extend Blagoveshchenskii equation to our class of systems\nwith persistent memory.\n",
"title": "Identification of a space varying coefficient of a linear viscoelastic string of Maxwell-Boltzman type"
}
| null | null | null | null | true | null |
4551
| null |
Default
| null | null |
null |
{
"abstract": " Nonlinear optics, especially frequency mixing, underpins modern optical\ntechnology and scientific exploration in quantum optics, materials and life\nsciences, and optical communications. Since nonlinear effects are weak,\nefficient frequency mixing must accumulate over large interaction lengths\nrestricting the integration of nonlinear photonics with electronics and\nestablishing limitations on mixing processes due to the requirement of phase\nmatching. In this work we report efficient four-wave mixing over micron-scale\ninteraction lengths at telecoms wavelengths. We use an integrated plasmonic gap\nwaveguide on silicon that strongly confines light within a nonlinear organic\npolymer in the gap. Our approach is so effective because the gap waveguide\nintensifies light by efficiently nanofocusing it to a mode cross-section of a\nfew tens of nanometres, generating a nonlinear response so strong that\nefficient four-wave mixing accumulates in just a micron. This is significant as\nour technique opens up nonlinear optics to a regime where phase matching and\ndispersion considerations are relaxed, giving rise to the possibility of\ncompact, broadband, and efficient frequency mixing on a platform that can be\nintegrated with silicon photonics.\n",
"title": "Efficient four-wave mixing at the nanofocus of integrated organic gap plasmon waveguides on silicon"
}
| null | null | null | null | true | null |
4552
| null |
Default
| null | null |
null |
{
"abstract": " The microcanonical Gross--Pitaevskii (aka semiclassical Bose-Hubbard) lattice\nmodel dynamics is characterized by a pair of energy and norm densities. The\ngrand canonical Gibbs distribution fails to describe a part of the density\nspace, due to the boundedness of its kinetic energy spectrum. We define\nPoincare equilibrium manifolds and compute the statistics of microcanonical\nexcursion times off them. The tails of the distribution functions quantify the\nproximity of the many-body dynamics to a weakly-nonergodic phase, which occurs\nwhen the average excursion time is infinite. We find that a crossover to\nweakly-nonergodic dynamics takes place inside the nonGibbs phase, being\nunnoticed by the largest Lyapunov exponent. In the ergodic part of the\nnon-Gibbs phase, the Gibbs distribution should be replaced by an unknown\nmodified one. We relate our findings to the corresponding integrable limit,\nclose to which the actions are interacting through a short range coupling\nnetwork.\n",
"title": "Weakly nonergodic dynamics in the Gross--Pitaevskii lattice"
}
| null | null | null | null | true | null |
4553
| null |
Default
| null | null |
null |
{
"abstract": " During the last decades, public policies become a central pillar in\nsupporting and stabilising agricultural sector. In 1962, EU policy-makers\ndeveloped the so-called Common Agricultural Policy (CAP) to ensure\ncompetitiveness and a common market organisation for agricultural products,\nwhile 2003 reform decouple the CAP from the production to focus only on income\nstabilization and the sustainability of agricultural sector. Notwithstanding\nfarmers are highly dependent to public support, literature on the role played\nby the CAP in fostering agricultural performances is still scarce and\nfragmented. Actual CAP policies increases performance differentials between\nNorthern Central EU countries and peripheral regions. This paper aims to\nevaluate the effectiveness of CAP in stimulate performances by focusing on\nItalian lagged Regions. Moreover, agricultural sector is deeply rooted in\nplace-based production processes. In this sense, economic analysis which omit\nthe presence of spatial dependence produce biased estimates of the\nperformances. Therefore, this paper, using data on subsidies and economic\nresults of farms from the RICA dataset which is part of the Farm Accountancy\nData Network (FADN), proposes a spatial Augmented Cobb-Douglas Production\nFunction to evaluate the effects of subsidies on farm's performances. The major\ninnovation in this paper is the implementation of a micro-founded quantile\nversion of a spatial lag model to examine how the impact of the subsidies may\nvary across the conditional distribution of agricultural performances. Results\nshow an increasing shape which switch from negative to positive at the median\nand becomes statistical significant for higher quantiles. Additionally, spatial\nautocorrelation parameter is positive and significant across all the\nconditional distribution, suggesting the presence of significant spatial\nspillovers in agricultural performances.\n",
"title": "Does agricultural subsidies foster Italian southern farms? A Spatial Quantile Regression Approach"
}
| null | null | null | null | true | null |
4554
| null |
Default
| null | null |
null |
{
"abstract": " Using two-dimensional hybrid expanding box simulations we study the\ncompetition between the continuously driven parallel proton temperature\nanisotropy and fire hose instabilities in collisionless homogeneous plasmas.\nFor quasi radial ambient magnetic field the expansion drives\n$T_{\\mathrm{p}\\|}>T_{\\mathrm{p}\\perp}$ and the system becomes eventually\nunstable with respect to the dominant parallel fire hose instability. This\ninstability is generally unable to counteract the induced anisotropization and\nthe system typically becomes unstable with respect to the oblique fire hose\ninstability later on. The oblique instability efficiently reduces the\nanisotropy and the system rapidly stabilizes while a significant part of the\ngenerated electromagnetic fluctuations is damped to protons. As long as the\nmagnetic field is in the quasi radial direction, this evolution repeats itself\nand the electromagnetic fluctuations accumulate. For sufficiently oblique\nmagnetic field the expansion drives $T_{\\mathrm{p}\\perp}>T_{\\mathrm{p}\\|}$ and\nbrings the system to the stable region with respect to the fire hose\ninstabilities.\n",
"title": "Proton fire hose instabilities in the expanding solar wind"
}
| null | null | null | null | true | null |
4555
| null |
Default
| null | null |
null |
{
"abstract": " We establish minimax optimal rates of convergence for nonparametric\nestimation in functional ANOVA models when data from first-order partial\nderivatives are available. Our results reveal that partial derivatives can\nimprove convergence rates for function estimation with deterministic or random\ndesigns. In particular, for full $d$-interaction models, the optimal rates with\nfirst-order partial derivatives on $p$ covariates are identical to those for\n$(d-p)$-interaction models without partial derivatives. For additive models,\nthe rates by using all first-order partial derivatives are root-$n$ to achieve\nthe \"parametric rate\". We also investigate the minimax optimal rates for\nfirst-order partial derivative estimations when derivative data are available.\nThose rates coincide with the optimal rate for estimating the first-order\nderivative of a univariate function.\n",
"title": "Minimax Optimal Rates of Estimation in Functional ANOVA Models with Derivatives"
}
| null | null |
[
"Mathematics",
"Statistics"
] | null | true | null |
4556
| null |
Validated
| null | null |
null |
{
"abstract": " We consider the problem of phase retrieval, i.e. that of solving systems of\nquadratic equations. A simple variant of the randomized Kaczmarz method was\nrecently proposed for phase retrieval, and it was shown numerically to have a\ncomputational edge over state-of-the-art Wirtinger flow methods. In this paper,\nwe provide the first theoretical guarantee for the convergence of the\nrandomized Kaczmarz method for phase retrieval. We show that it is sufficient\nto have as many Gaussian measurements as the dimension, up to a constant\nfactor. Along the way, we introduce a sufficient condition on measurement sets\nfor which the randomized Kaczmarz method is guaranteed to work. We show that\nGaussian sampling vectors satisfy this property with high probability; this is\nproved using a chaining argument coupled with bounds on VC dimension and metric\nentropy.\n",
"title": "Phase Retrieval via Randomized Kaczmarz: Theoretical Guarantees"
}
| null | null | null | null | true | null |
4557
| null |
Default
| null | null |
null |
{
"abstract": " It is shown that if one uses the notion of infinity nilpotent elements due to\nMoerdijk and Reyes, instead of the usual definition of nilpotents to define\nreduced $C^\\infty$-schemes, the resulting de Rham spaces are given as quotients\nby actions of germs of diagonals, instead of the formal neighbourhoods of the\ndiagonals.\n",
"title": "Beyond perturbation 1: de Rham spaces"
}
| null | null | null | null | true | null |
4558
| null |
Default
| null | null |
null |
{
"abstract": " Internet as become the way of life in the fast growing digital life.Even with\nthe increase in the internet speed, higher latency time is still a challenge.\nTo reduce latency, caching and pre fetching techniques can be used. However,\ncaching fails for dynamic websites which keeps on changing rapidly. Another\ntechnique is web prefetching, which prefetches the web pages that the user is\nlikely to request for in the future. Semantic web prefetching makes use of\nkeywords and descriptive texts like anchor text, titles, text surrounding\nanchor text of the present web pages for predicting users future requests.\nSemantic information is embedded within the web pages during their designing\nfor the purpose of reflecting the relationship between the web pages. The\nclient can fetch this information from the server. However, this technique\ninvolves load on web designers for adding external tags and on server for\nproviding this information along with the desired page, which is not desirable.\nThis paper is an effort to find the semantic relation between web pages using\nthe keywords provided by the user and the anchor texts of the hyperlinks on the\npresent web page.It provides algorithms for sequential and similar semantic\nrelations. These algorithms will be implemented on the client side which will\nnot cause overhead on designers and load on server for semantic information.\n",
"title": "Semantic Web Prefetching Using Semantic Relatedness between Web pages"
}
| null | null | null | null | true | null |
4559
| null |
Default
| null | null |
null |
{
"abstract": " We present the design and implementation of a custom discrete optimization\ntechnique for building rule lists over a categorical feature space. Our\nalgorithm produces rule lists with optimal training performance, according to\nthe regularized empirical risk, with a certificate of optimality. By leveraging\nalgorithmic bounds, efficient data structures, and computational reuse, we\nachieve several orders of magnitude speedup in time and a massive reduction of\nmemory consumption. We demonstrate that our approach produces optimal rule\nlists on practical problems in seconds. Our results indicate that it is\npossible to construct optimal sparse rule lists that are approximately as\naccurate as the COMPAS proprietary risk prediction tool on data from Broward\nCounty, Florida, but that are completely interpretable. This framework is a\nnovel alternative to CART and other decision tree methods for interpretable\nmodeling.\n",
"title": "Learning Certifiably Optimal Rule Lists for Categorical Data"
}
| null | null | null | null | true | null |
4560
| null |
Default
| null | null |
null |
{
"abstract": " Policy-gradient approaches to reinforcement learning have two common and\nundesirable overhead procedures, namely warm-start training and sample variance\nreduction. In this paper, we describe a reinforcement learning method based on\na softmax value function that requires neither of these procedures. Our method\ncombines the advantages of policy-gradient methods with the efficiency and\nsimplicity of maximum-likelihood approaches. We apply this new cold-start\nreinforcement learning method in training sequence generation models for\nstructured output prediction problems. Empirical evidence validates this method\non automatic summarization and image captioning tasks.\n",
"title": "Cold-Start Reinforcement Learning with Softmax Policy Gradient"
}
| null | null | null | null | true | null |
4561
| null |
Default
| null | null |
null |
{
"abstract": " Absolute positioning of vehicles is based on Global Navigation Satellite\nSystems (GNSS) combined with on-board sensors and high-resolution maps. In\nCooperative Intelligent Transportation Systems (C-ITS), the positioning\nperformance can be augmented by means of vehicular networks that enable\nvehicles to share location-related information. This paper presents an Implicit\nCooperative Positioning (ICP) algorithm that exploits the Vehicle-to-Vehicle\n(V2V) connectivity in an innovative manner, avoiding the use of explicit V2V\nmeasurements such as ranging. In the ICP approach, vehicles jointly localize\nnon-cooperative physical features (such as people, traffic lights or inactive\ncars) in the surrounding areas, and use them as common noisy reference points\nto refine their location estimates. Information on sensed features are fused\nthrough V2V links by a consensus procedure, nested within a message passing\nalgorithm, to enhance the vehicle localization accuracy. As positioning does\nnot rely on explicit ranging information between vehicles, the proposed ICP\nmethod is amenable to implementation with off-the-shelf vehicular communication\nhardware. The localization algorithm is validated in different traffic\nscenarios, including a crossroad area with heterogeneous conditions in terms of\nfeature density and V2V connectivity, as well as a real urban area by using\nSimulation of Urban MObility (SUMO) for traffic data generation. Performance\nresults show that the proposed ICP method can significantly improve the vehicle\nlocation accuracy compared to the stand-alone GNSS, especially in harsh\nenvironments, such as in urban canyons, where the GNSS signal is highly\ndegraded or denied.\n",
"title": "Implicit Cooperative Positioning in Vehicular Networks"
}
| null | null | null | null | true | null |
4562
| null |
Default
| null | null |
null |
{
"abstract": " We demonstrate that the augmented estimate sequence framework unites the most\npopular primal first-order schemes for large-scale problems: the Fast Gradient\nMethod (FGM) and the Fast Iterative Shrinkage Thresholding Algorithm (FISTA).\nWe further showcase the flexibility of the augmented estimate sequence by\nderiving a Generalized Accelerated Composite Gradient Method endowed with\nmonotonicity alongside a versatile line-search procedure. The new method\nsurpasses both FGM and FISTA in terms of robustness and usability. In\nparticular, it is guaranteed to converge without requiring any quantitative\nprior information on the problem. Additional information, if available, leads\nto an improvement in performance at least on par with the state-of-the-art. We\nsupport our findings with simulation results.\n",
"title": "A Generalized Accelerated Composite Gradient Method: Uniting Nesterov's Fast Gradient Method and FISTA"
}
| null | null | null | null | true | null |
4563
| null |
Default
| null | null |
null |
{
"abstract": " The interplay between electrochemical surface charges and bulk\nferroelectricity in thin films gives rise to a continuum of coupled ferro-ionic\nstates. These states are exquisitely sensitive to chemical and electric\nconditions at the surfaces, applied voltage, and oxygen pressure. Using the\nanalytical approach combining the Ginzburg-Landau-Devonshire description of the\nferroelectricity with Langmuir adsorption isotherm for the ions at the film\nsurface, we have studied the temperature-, time- and field- dependent\npolarization changes and electromechanical response of the ferro-ionic states.\nThe responses are found to be inseparable in thermodynamic equilibrium and at\nlow frequencies of applied voltage. The states become separable in high\nfrequency dynamic mode due to the several orders of magnitude difference in the\nrelaxation times of ferroelectric polarization and surface ions charge density.\nThese studies provide an insight into dynamic behavior of nanoscale\nferroelectrics with open surface exposed to different kinds of\nelectrochemically active gaseous surrounding.\n",
"title": "Piezoresponse of ferroelectric films in ferroionic states: time and voltage dynamics"
}
| null | null |
[
"Physics"
] | null | true | null |
4564
| null |
Validated
| null | null |
null |
{
"abstract": " Feasibility pumps are highly effective primal heuristics for mixed-integer\nlinear and nonlinear optimization. However, despite their success in practice\nthere are only few works considering their theoretical properties. We show that\nfeasibility pumps can be seen as alternating direction methods applied to\nspecial reformulations of the original problem, inheriting the convergence\ntheory of these methods. Moreover, we propose a novel penalty framework that\nencompasses this alternating direction method, which allows us to refrain from\nrandom perturbations that are applied in standard versions of feasibility pumps\nin case of failure. We present a convergence theory for the new penalty based\nalternating direction method and compare the new variant of the feasibility\npump with existing versions in an extensive numerical study for mixed-integer\nlinear and nonlinear problems.\n",
"title": "Penalty Alternating Direction Methods for Mixed-Integer Optimization: A New View on Feasibility Pumps"
}
| null | null | null | null | true | null |
4565
| null |
Default
| null | null |
null |
{
"abstract": " Starting from covariant expressions, a gauge independent separation of\norbital and spin angular momentum for electrodynamics is presented. This\nresults from the non-symmetric canonical energy momentum tensor of the\nelectromagnetic field. The origin of the difficulty is discussed and a\ncovariant gauge invariant spin vector is derived. The paradox concerning the\nspin angular momentum of a plane wave finds a natural solution.\n",
"title": "Lorentz covariant and gauge invariant description of orbital and spin angular momentum and the non-symmetric energy momentum tensor"
}
| null | null | null | null | true | null |
4566
| null |
Default
| null | null |
null |
{
"abstract": " If $a$ and $d$ are relatively prime, we refer to the set of integers\ncongruent to $a$ mod $d$ as an `eligible' arithmetic progression. A theorem of\nDirichlet says that every eligible arithmetic progression contains infinitely\nmany primes; the theorem follows from the assertion that every eligible\narithmetic progression contains at least one prime. The Jacobsthal function\n$g(n)$ is defined as the smallest positive integer such that every sequence of\n$g(n)$ consecutive integers contains an integer relatively prime to $n$. In\nthis paper, we show by a combinatorial argument that every eligible arithmetic\nprogression with $d\\le76$ contains at least one prime, and we show that certain\nplausible bounds on the Jacobsthal function of primorials would imply that\nevery eligible arithmetic progression contains at least one prime. That is,\ncertain plausible bounds on the Jacobsthal function would lead to an elementary\nproof of Dirichlet's theorem.\n",
"title": "Dirichlet's theorem and Jacobsthal's function"
}
| null | null | null | null | true | null |
4567
| null |
Default
| null | null |
null |
{
"abstract": " We develop an asymptotical control theory for one of the simplest distributed\noscillating systems, namely, for a closed string under a bounded load applied\nto a single distinguished point. We find exact classes of string states that\nadmit complete damping and an asymptotically exact value of the required time.\nBy using approximate reachable sets instead of exact ones, we design a\ndry-friction like feedback control, which turns out to be asymptotically\noptimal. We prove the existence of motion under the control using a rather\nexplicit solution of a nonlinear wave equation. Remarkably, the solution is\ndetermined via purely algebraic operations. The main result is a proof of\nasymptotic optimality of the control thus constructed.\n",
"title": "Asymptotic control theory for a closed string"
}
| null | null | null | null | true | null |
4568
| null |
Default
| null | null |
null |
{
"abstract": " Replication is complicated in psychological research because studies of a\ngiven psychological phenomenon can never be direct or exact replications of one\nanother, and thus effect sizes vary from one study of the phenomenon to the\nnext--an issue of clear importance for replication. Current large scale\nreplication projects represent an important step forward for assessing\nreplicability, but provide only limited information because they have thus far\nbeen designed in a manner such that heterogeneity either cannot be assessed or\nis intended to be eliminated. Consequently, the non-trivial degree of\nheterogeneity found in these projects represents a lower bound on\nheterogeneity. We recommend enriching large scale replication projects going\nforward by em- bracing heterogeneity. We argue this is key for assessing\nreplicability: if effect sizes are sufficiently heterogeneous--even if the sign\nof the effect is consistent--the phenomenon in question does not seem\nparticularly replicable and the theory underlying it seems poorly constructed\nand in need of enrichment. Uncovering why and revising theory in light of it\nwill lead to improved theory that explains heterogeneity and in- creases\nreplicability. Given this, large scale replication projects can play an\nimportant role not only in assessing replicability but also in advancing\ntheory.\n",
"title": "Large Scale Replication Projects in Contemporary Psychological Research"
}
| null | null | null | null | true | null |
4569
| null |
Default
| null | null |
null |
{
"abstract": " We study the angular dependence of the dissipation in the superconducting\nstate of FeSe and Fe(Se$_\\text{1-x}$Te$_\\text{x}$) through electrical transport\nmeasurements, using crystalline intergrown materials. We reveal the key role of\nthe inclusions of the non superconducting magnetic phase\nFe$_\\text{1-y}$(Se$_\\text{1-x}$Te$_\\text{x}$), growing into the\nFe(Se$_\\text{1-x}$Te$_\\text{x}$) pure $\\beta$-phase, in the development of a\ncorrelated defect structure. The matching of both atomic structures defines the\ngrowth habit of the crystalline material as well as the correlated planar\ndefects orientation.\n",
"title": "Intrinsic pinning by naturally occurring correlated defects in FeSe$_\\text{1-x}$Te$_\\text{x}$ superconductors"
}
| null | null | null | null | true | null |
4570
| null |
Default
| null | null |
null |
{
"abstract": " The displacement calculus $\\mathbf{D}$ is a conservative extension of the\nLambek calculus $\\mathbf{L1}$ (with empty antecedents allowed in sequents).\n$\\mathbf{L1}$ can be said to be the logic of concatenation, while $\\mathbf{D}$\ncan be said to be the logic of concatenation and intercalation. In many senses,\nit can be claimed that $\\mathbf{D}$ mimics $\\mathbf{L1}$ in that the proof\ntheory, generative capacity and complexity of the former calculus are natural\nextensions of the latter calculus. In this paper, we strengthen this claim. We\npresent the appropriate classes of models for $\\mathbf{D}$ and prove some\ncompleteness results; strikingly, we see that these results and proofs are\nnatural extensions of the corresponding ones for $\\mathbf{L1}$.\n",
"title": "Models for the Displacement Calculus"
}
| null | null | null | null | true | null |
4571
| null |
Default
| null | null |
null |
{
"abstract": " We construct labeling homomorphisms on the cubical homology of\nhigher-dimensional automata and show that they are natural with respect to\ncubical dimaps and compatible with the tensor product of HDAs. We also indicate\ntwo possible applications of labeled homology in concurrency theory.\n",
"title": "Labeled homology of higher-dimensional automata"
}
| null | null |
[
"Computer Science",
"Mathematics"
] | null | true | null |
4572
| null |
Validated
| null | null |
null |
{
"abstract": " We demonstrate the integration of a mesoscopic ferromagnetic needle with a\ncavity optomechanical torsional resonator, and its use for quantitative\ndetermination of the needle's magnetic properties, as well as amplification and\ncooling of the resonator motion. With this system we measure torques as small\nas 32 zNm, corresponding to sensing an external magnetic field of 0.12 A/m (150\nnT). Furthermore, we are able to extract the magnetization (1710 kA/m) of the\nmagnetic sample, not known a priori, demonstrating this system's potential for\nstudies of nanomagnetism. Finally, we show that we can magnetically drive the\ntorsional resonator into regenerative oscillations, and dampen its mechanical\nmode temperature from room temperature to 11.6 K, without sacrificing torque\nsensitivity.\n",
"title": "Magnetic Actuation and Feedback Cooling of a Cavity Optomechanical Torque Sensor"
}
| null | null | null | null | true | null |
4573
| null |
Default
| null | null |
null |
{
"abstract": " We present a solution to scale spectral algorithms for learning sequence\nfunctions. We are interested in the case where these functions are sparse (that\nis, for most sequences they return 0). Spectral algorithms reduce the learning\nproblem to the task of computing an SVD decomposition over a special type of\nmatrix called the Hankel matrix. This matrix is designed to capture the\nrelevant statistics of the training sequences. What is crucial is that to\ncapture long range dependencies we must consider very large Hankel matrices.\nThus the computation of the SVD becomes a critical bottleneck. Our solution\nfinds a subset of rows and columns of the Hankel that realizes a compact and\ninformative Hankel submatrix. The novelty lies in the way that this subset is\nselected: we exploit a maximal bipartite matching combinatorial algorithm to\nlook for a sub-block with full structural rank, and show how computation of\nthis sub-block can be further improved by exploiting the specific structure of\nHankel matrices.\n",
"title": "A Maximum Matching Algorithm for Basis Selection in Spectral Learning"
}
| null | null |
[
"Computer Science",
"Statistics"
] | null | true | null |
4574
| null |
Validated
| null | null |
null |
{
"abstract": " The Bäcklund transformation (BT) for the \"good\" Boussinesq equation and its\nsuperposition principles are presented and applied. Unlike many other standard\nintegrable equations, the Boussinesq equation does not have a strictly\nalgebraic superposition principle for 2 BTs, but it does for 3. We present\nassociated lattice systems. Applying the BT to the trivial solution generates\nstandard solitons but also what we call \"merging solitons\" --- solutions in\nwhich two solitary waves (with related speeds) merge into a single one. We use\nthe superposition principles to generate a variety of interesting solutions,\nincluding superpositions of a merging soliton with $1$ or $2$ regular solitons,\nand solutions that develop a singularity in finite time which then disappears\nat some later finite time. We prove a Wronskian formula for the solutions\nobtained by applying a general sequence of BTs on the trivial solution.\nFinally, we show how to obtain the standard conserved quantities of the\nBoussinesq equation from the BT, and how the hierarchy of local symmetries\nfollows in a simple manner from the superposition principle for 3 BTs.\n",
"title": "Bäcklund Transformations for the Boussinesq Equation and Merging Solitons"
}
| null | null | null | null | true | null |
4575
| null |
Default
| null | null |
null |
{
"abstract": " Compressing convolutional neural networks (CNNs) is essential for\ntransferring the success of CNNs to a wide variety of applications to mobile\ndevices. In contrast to directly recognizing subtle weights or filters as\nredundant in a given CNN, this paper presents an evolutionary method to\nautomatically eliminate redundant convolution filters. We represent each\ncompressed network as a binary individual of specific fitness. Then, the\npopulation is upgraded at each evolutionary iteration using genetic operations.\nAs a result, an extremely compact CNN is generated using the fittest\nindividual. In this approach, either large or small convolution filters can be\nredundant, and filters in the compressed network are more distinct. In\naddition, since the number of filters in each convolutional layer is reduced,\nthe number of filter channels and the size of feature maps are also decreased,\nnaturally improving both the compression and speed-up ratios. Experiments on\nbenchmark deep CNN models suggest the superiority of the proposed algorithm\nover the state-of-the-art compression methods.\n",
"title": "Towards Evolutional Compression"
}
| null | null | null | null | true | null |
4576
| null |
Default
| null | null |
null |
{
"abstract": " We consider a dilute fluorinated graphene nanoribbon as a spin-active\nelement. The fluorine adatoms introduce a local spin-orbit Rashba interaction\nthat induces spin-precession for electron passing by. In the absence of the\nexternal magnetic field the transport is dominated by multiple scattering by\nadatoms which cancels the spin precession effects, since the direction of the\nspin precession depends on the electron momentum. Accumulation of the spin\nprecession effects is possible provided that the Fermi level electron passes\nmany times near the same adatom with the same momentum. In order to arrange for\nthese conditions a circular n-p junction can be introduced to the ribbon by\ne.g. potential of the tip of an atomic force microscope. In the quantum Hall\nconditions the electron current gets confined along the junction. The electron\nspin interaction with the local Rashba field changes with the lifetime of the\nquasi-bound states that is controlled with the coupling of the junction to the\nedge of the ribbon. We demonstrate that the spin-flip probability can be\nincreased in this manner by as much as three orders of magnitude.\n",
"title": "Spin inversion in fluorinated graphene n-p junction"
}
| null | null |
[
"Physics"
] | null | true | null |
4577
| null |
Validated
| null | null |
null |
{
"abstract": " Given one metric measure space $X$ satisfying a linear Brunn-Minkowski\ninequality, and a second one $Y$ satisfying a Brunn-Minkowski inequality with\nexponent $p\\ge -1$, we prove that the product $X\\times Y$ with the standard\nproduct distance and measure satisfies a Brunn-Minkowski inequality of order\n$1/(1+p^{-1})$ under mild conditions on the measures and the assumption that\nthe distances are strictly intrinsic. The same result holds when we consider\nrestricted classes of sets. We also prove that a linear Brunn-Minkowski\ninequality is obtained in $X\\times Y$ when $Y$ satisfies a Prékopa-Leindler\ninequality.\nIn particular, we show that the classical Brunn-Minkowski inequality holds\nfor any pair of weakly unconditional sets in $\\mathbb{R}^n$ (i.e., those\ncontaining the projection of every point in the set onto every coordinate\nsubspace) when we consider the standard distance and the product measure of $n$\none-dimensional real measures with positively decreasing densities. This yields\nan improvement of the class of sets satisfying the Gaussian Brunn-Minkowski\ninequality.\nFurthermore, associated isoperimetric inequalities as well as recently\nobtained Brunn-Minkowski's inequalities are derived from our results.\n",
"title": "Brunn-Minkowski inequalities in product metric measure spaces"
}
| null | null | null | null | true | null |
4578
| null |
Default
| null | null |
null |
{
"abstract": " The problem of quantizing the activations of a deep neural network is\nconsidered. An examination of the popular binary quantization approach shows\nthat this consists of approximating a classical non-linearity, the hyperbolic\ntangent, by two functions: a piecewise constant sign function, which is used in\nfeedforward network computations, and a piecewise linear hard tanh function,\nused in the backpropagation step during network learning. The problem of\napproximating the ReLU non-linearity, widely used in the recent deep learning\nliterature, is then considered. An half-wave Gaussian quantizer (HWGQ) is\nproposed for forward approximation and shown to have efficient implementation,\nby exploiting the statistics of of network activations and batch normalization\noperations commonly used in the literature. To overcome the problem of gradient\nmismatch, due to the use of different forward and backward approximations,\nseveral piece-wise backward approximators are then investigated. The\nimplementation of the resulting quantized network, denoted as HWGQ-Net, is\nshown to achieve much closer performance to full precision networks, such as\nAlexNet, ResNet, GoogLeNet and VGG-Net, than previously available low-precision\nnetworks, with 1-bit binary weights and 2-bit quantized activations.\n",
"title": "Deep Learning with Low Precision by Half-wave Gaussian Quantization"
}
| null | null |
[
"Computer Science"
] | null | true | null |
4579
| null |
Validated
| null | null |
null |
{
"abstract": " We associate a monoidal category $\\mathcal{H}^\\lambda$ to each dominant\nintegral weight $\\lambda$ of $\\widehat{\\mathfrak{sl}}_p$ or\n$\\mathfrak{sl}_\\infty$. These categories, defined in terms of planar diagrams,\nact naturally on categories of modules for the degenerate cyclotomic Hecke\nalgebras associated to $\\lambda$. We show that, in the $\\mathfrak{sl}_\\infty$\ncase, the level $d$ Heisenberg algebra embeds into the Grothendieck ring of\n$\\mathcal{H}^\\lambda$, where $d$ is the level of $\\lambda$. The categories\n$\\mathcal{H}^\\lambda$ can be viewed as a graphical calculus describing\ninduction and restriction functors between categories of modules for degenerate\ncyclotomic Hecke algebras, together with their natural transformations. As an\napplication of this tool, we prove a new result concerning centralizers for\ndegenerate cyclotomic Hecke algebras.\n",
"title": "Degenerate cyclotomic Hecke algebras and higher level Heisenberg categorification"
}
| null | null |
[
"Mathematics"
] | null | true | null |
4580
| null |
Validated
| null | null |
null |
{
"abstract": " Let $G$ be a group. An automorphism of $G$ is called intense if it sends each\nsubgroup of $G$ to a conjugate; the collection of such automorphisms is denoted\nby $\\mathrm{Int}(G)$. In the special case in which $p$ is a prime number and\n$G$ is a finite $p$-group, one can show that $\\mathrm{Int}(G)$ is the\nsemidirect product of a normal $p$-Sylow and a cyclic subgroup of order\ndividing $p-1$. In this thesis we classify the finite $p$-groups whose groups\nof intense automorphisms are not themselves $p$-groups. It emerges from our\ninvestigation that the structure of such groups is almost completely determined\nby their nilpotency class: for $p>3$, they share a quotient, growing with their\nclass, with a uniquely determined infinite $2$-generated pro-$p$ group.\n",
"title": "Intense automorphisms of finite groups"
}
| null | null | null | null | true | null |
4581
| null |
Default
| null | null |
null |
{
"abstract": " We study the adjoint of the double layer potential associated with the\nLaplacian (the adjoint of the Neumann-Poincaré operator), as a map on the\nboundary surface $\\Gamma$ of a domain in $\\mathbb{R}^3$ with conical points.\nThe spectrum of this operator directly reflects the well-posedness of related\ntransmission problems across $\\Gamma$. In particular, if the domain is\nunderstood as an inclusion with complex permittivity $\\epsilon$, embedded in a\nbackground medium with unit permittivity, then the polarizability tensor of the\ndomain is well-defined when $(\\epsilon+1)/(\\epsilon-1)$ belongs to the\nresolvent set in energy norm. We study surfaces $\\Gamma$ that have a finite\nnumber of conical points featuring rotational symmetry. On the energy space, we\nshow that the essential spectrum consists of an interval. On $L^2(\\Gamma)$,\ni.e. for square-integrable boundary data, we show that the essential spectrum\nconsists of a countable union of curves, outside of which the Fredholm index\ncan be computed as a winding number with respect to the essential spectrum. We\nprovide explicit formulas, depending on the opening angles of the conical\npoints. We reinforce our study with very precise numerical experiments,\ncomputing the energy space spectrum and the spectral measures of the\npolarizability tensor in two different examples. Our results indicate that the\ndensities of the spectral measures may approach zero extremely rapidly in the\ncontinuous part of the energy space spectrum.\n",
"title": "The spectra of harmonic layer potential operators on domains with rotationally symmetric conical points"
}
| null | null | null | null | true | null |
4582
| null |
Default
| null | null |
null |
{
"abstract": " The structural coefficient of restitution describes the kinetic energy\ndissipation upon low-velocity (~0.1 m/s) impact of a small asteroid lander,\nMASCOT, against a hard, ideally elastic plane surface. It is a crucial\nworst-case input for mission analysis for landing MACOT on a 1km asteroid in\n2018. We conducted pendulum tests and describe their analysis and the results.\n",
"title": "Experimental Determination of the Structural Coefficient of Restitution of a Bouncing Asteroid Lander"
}
| null | null | null | null | true | null |
4583
| null |
Default
| null | null |
null |
{
"abstract": " We explore the phase diagram of a finite-sized dysprosium dipolar\nBose-Einstein condensate in a cylindrical harmonic trap. We monitor the final\nstate after the scattering length is lowered from the repulsive BEC regime to\nthe quantum droplet regime. Either an adiabatic transformation between a BEC\nand a quantum droplet is obtained or, above a critical trap aspect ratio\n$\\lambda_{\\rm c}=1.87(14)$, a modulational instability results in the formation\nof multiple droplets. This is in full agreement with the predicted structure of\nthe phase diagram with a crossover region below $\\lambda_{\\rm c}$ and a\nmultistable region above. Our results provide the missing piece connecting the\npreviously explored regimes resulting in a single or multiple dipolar quantum\ndroplets.\n",
"title": "Onset of a modulational instability in trapped dipolar Bose-Einstein condensates"
}
| null | null | null | null | true | null |
4584
| null |
Default
| null | null |
null |
{
"abstract": " Topological data analysis is an emerging area in exploratory data analysis\nand data mining. Its main tool, persistent homology, has become a popular\ntechnique to study the structure of complex, high-dimensional data. In this\npaper, we propose a novel method using persistent homology to quantify\nstructural changes in time-varying graphs. Specifically, we transform each\ninstance of the time-varying graph into metric spaces, extract topological\nfeatures using persistent homology, and compare those features over time. We\nprovide a visualization that assists in time-varying graph exploration and\nhelps to identify patterns of behavior within the data. To validate our\napproach, we conduct several case studies on real world data sets and show how\nour method can find cyclic patterns, deviations from those patterns, and\none-time events in time-varying graphs. We also examine whether\npersistence-based similarity measure as a graph metric satisfies a set of\nwell-established, desirable properties for graph metrics.\n",
"title": "Visual Detection of Structural Changes in Time-Varying Graphs Using Persistent Homology"
}
| null | null | null | null | true | null |
4585
| null |
Default
| null | null |
null |
{
"abstract": " In this paper, we design nonlinear state feedback controllers for\ndiscrete-time polynomial dynamical systems via the occupation measure approach.\nWe propose the discrete-time controlled Liouville equation, and use it to\nformulate the controller synthesis problem as an infinite-dimensional linear\nprogramming problem on measures, which is then relaxed as finite-dimensional\nsemidefinite programming problems on moments of measures and their duals on\nsums-of-squares polynomials. Nonlinear controllers can be extracted from the\nsolutions to the relaxed problems. The advantage of the occupation measure\napproach is that we solve convex problems instead of generally non-convex\nproblems, and the computational complexity is polynomial in the state and input\ndimensions, and hence the approach is more scalable. In addition, we show that\nthe approach can be applied to over-approximating the backward reachable set of\ndiscrete-time autonomous polynomial systems and the controllable set of\ndiscrete-time polynomial systems under known state feedback control laws. We\nillustrate our approach on several dynamical systems.\n",
"title": "Controller Synthesis for Discrete-Time Polynomial Systems via Occupation Measures"
}
| null | null | null | null | true | null |
4586
| null |
Default
| null | null |
null |
{
"abstract": " Computed Tomography (CT) reconstruction is a fundamental component to a wide\nvariety of applications ranging from security, to healthcare. The classical\ntechniques require measuring projections, called sinograms, from a full\n180$^\\circ$ view of the object. This is impractical in a limited angle\nscenario, when the viewing angle is less than 180$^\\circ$, which can occur due\nto different factors including restrictions on scanning time, limited\nflexibility of scanner rotation, etc. The sinograms obtained as a result, cause\nexisting techniques to produce highly artifact-laden reconstructions. In this\npaper, we propose to address this problem through implicit sinogram completion,\non a challenging real world dataset containing scans of common checked-in\nluggage. We propose a system, consisting of 1D and 2D convolutional neural\nnetworks, that operates on a limited angle sinogram to directly produce the\nbest estimate of a reconstruction. Next, we use the x-ray transform on this\nreconstruction to obtain a \"completed\" sinogram, as if it came from a full\n180$^\\circ$ measurement. We feed this to standard analytical and iterative\nreconstruction techniques to obtain the final reconstruction. We show with\nextensive experimentation that this combined strategy outperforms many\ncompetitive baselines. We also propose a measure of confidence for the\nreconstruction that enables a practitioner to gauge the reliability of a\nprediction made by our network. We show that this measure is a strong indicator\nof quality as measured by the PSNR, while not requiring ground truth at test\ntime. Finally, using a segmentation experiment, we show that our reconstruction\npreserves the 3D structure of objects effectively.\n",
"title": "Lose The Views: Limited Angle CT Reconstruction via Implicit Sinogram Completion"
}
| null | null | null | null | true | null |
4587
| null |
Default
| null | null |
null |
{
"abstract": " We consider bounded solutions of the nonlocal Allen-Cahn equation $$\n(-\\Delta)^s u=u-u^3\\qquad{\\mbox{ in }}{\\mathbb{R}}^3,$$ under the monotonicity\ncondition $\\partial_{x_3}u>0$ and in the genuinely nonlocal regime in\nwhich~$s\\in\\left(0,\\frac12\\right)$. Under the limit assumptions $$\n\\lim_{x_n\\to-\\infty} u(x',x_n)=-1\\quad{\\mbox{ and }}\\quad \\lim_{x_n\\to+\\infty}\nu(x',x_n)=1,$$ it has been recently shown that~$u$ is necessarily $1$D, i.e. it\ndepends only on one Euclidean variable. The goal of this paper is to obtain a\nsimilar result without assuming such limit conditions. This type of results can\nbe seen as nonlocal counterparts of the celebrated conjecture formulated by\nEnnio De Giorgi.\n",
"title": "A three-dimensional symmetry result for a phase transition equation in the genuinely nonlocal regime"
}
| null | null | null | null | true | null |
4588
| null |
Default
| null | null |
null |
{
"abstract": " Bi(0001) films with thicknesses up to several bilayers (BLs) are grown on\nSe-terminated Bi$_2$Se$_3$(0001) surfaces, and low energy electron diffraction\n(LEED), low energy ion scattering (LEIS) and atomic force microscopy (AFM) are\nused to investigate the surface composition, topography and atomic structure.\nFor a single deposited Bi BL, the lattice constant matches that of the\nsubstrate and the Bi atoms adjacent to the uppermost Se atoms are located at\nfcc-like sites. When a 2nd Bi bilayer is deposited, it is incommensurate with\nthe substrate. As the thickness of the deposited Bi film increases further, the\nlattice parameter evolves to that of bulk Bi(0001). After annealing a multiple\nBL film at 120°C, the first commensurate Bi BL remains intact, but the\nadditional BLs aggregate to form thicker islands of Bi. These results show that\na single Bi BL on Bi$_2$Se$_3$ is a particularly stable structure. After\nannealing to 490°C, all of the excess Bi desorbs and the Se-terminated\nBi$_2$Se$_3$ surface is restored.\n",
"title": "The growth of bismuth on Bi$_2$Se$_3$ and the stability of the first bilayer"
}
| null | null | null | null | true | null |
4589
| null |
Default
| null | null |
null |
{
"abstract": " Tensors are multidimensional arrays of numerical values and therefore\ngeneralize matrices to multiple dimensions. While tensors first emerged in the\npsychometrics community in the $20^{\\text{th}}$ century, they have since then\nspread to numerous other disciplines, including machine learning. Tensors and\ntheir decompositions are especially beneficial in unsupervised learning\nsettings, but are gaining popularity in other sub-disciplines like temporal and\nmulti-relational data analysis, too.\nThe scope of this paper is to give a broad overview of tensors, their\ndecompositions, and how they are used in machine learning. As part of this, we\nare going to introduce basic tensor concepts, discuss why tensors can be\nconsidered more rigid than matrices with respect to the uniqueness of their\ndecomposition, explain the most important factorization algorithms and their\nproperties, provide concrete examples of tensor decomposition applications in\nmachine learning, conduct a case study on tensor-based estimation of mixture\nmodels, talk about the current state of research, and provide references to\navailable software libraries.\n",
"title": "Introduction to Tensor Decompositions and their Applications in Machine Learning"
}
| null | null |
[
"Computer Science",
"Statistics"
] | null | true | null |
4590
| null |
Validated
| null | null |
null |
{
"abstract": " Consider a researcher estimating the parameters of a regression function\nbased on data for all 50 states in the United States or on data for all visits\nto a website. What is the interpretation of the estimated parameters and the\nstandard errors? In practice, researchers typically assume that the sample is\nrandomly drawn from a large population of interest and report standard errors\nthat are designed to capture sampling variation. This is common practice, even\nin applications where it is difficult to articulate what that population of\ninterest is, and how it differs from the sample. In this article, we explore an\nalternative approach to inference, which is partly design-based. In a\ndesign-based setting, the values of some of the regressors can be manipulated,\nperhaps through a policy intervention. Design-based uncertainty emanates from\nlack of knowledge about the values that the regression outcome would have taken\nunder alternative interventions. We derive standard errors that account for\ndesign-based uncertainty instead of, or in addition to, sampling-based\nuncertainty. We show that our standard errors in general are smaller than the\ninfinite-population sampling-based standard errors and provide conditions under\nwhich they coincide.\n",
"title": "Sampling-based vs. Design-based Uncertainty in Regression Analysis"
}
| null | null |
[
"Mathematics",
"Statistics"
] | null | true | null |
4591
| null |
Validated
| null | null |
null |
{
"abstract": " Missing data and noisy observations pose significant challenges for reliably\npredicting events from irregularly sampled multivariate time series\n(longitudinal) data. Imputation methods, which are typically used for\ncompleting the data prior to event prediction, lack a principled mechanism to\naccount for the uncertainty due to missingness. Alternatively, state-of-the-art\njoint modeling techniques can be used for jointly modeling the longitudinal and\nevent data and compute event probabilities conditioned on the longitudinal\nobservations. These approaches, however, make strong parametric assumptions and\ndo not easily scale to multivariate signals with many observations. Our\nproposed approach consists of several key innovations. First, we develop a\nflexible and scalable joint model based upon sparse multiple-output Gaussian\nprocesses. Unlike state-of-the-art joint models, the proposed model can explain\nhighly challenging structure including non-Gaussian noise while scaling to\nlarge data. Second, we derive an optimal policy for predicting events using the\ndistribution of the event occurrence estimated by the joint model. The derived\npolicy trades-off the cost of a delayed detection versus incorrect assessments\nand abstains from making decisions when the estimated event probability does\nnot satisfy the derived confidence criteria. Experiments on a large dataset\nshow that the proposed framework significantly outperforms state-of-the-art\ntechniques in event prediction.\n",
"title": "Scalable Joint Models for Reliable Uncertainty-Aware Event Prediction"
}
| null | null | null | null | true | null |
4592
| null |
Default
| null | null |
null |
{
"abstract": " Concurrent coding is an unconventional encoding technique that simultaneously\nprovides protection against noise, burst errors and interference. This\nsimple-to-understand concept is investigated by distinguishing 2 types of code,\nopen and closed, with the majority of the investigation concentrating on closed\ncodes. Concurrent coding is shown to possess an inherent method of\nsynchronisation thus requiring no additional synchronisation signals to be\nadded. This enables an isolated codeword transmission to be synchronised and\ndecoded in the presence of noise and burst errors. Comparisons are made with\nthe spread spectrum technique CDMA. With a like-for-like comparison concurrent\ncoding performs comparably against random noise effects, performs better\nagainst burst errors and is far superior in terms of transmitted energy\nefficiency\n",
"title": "Concurrent Coding: A Reason to Think Differently About Encoding Against Noise, Burst Errors and Jamming"
}
| null | null | null | null | true | null |
4593
| null |
Default
| null | null |
null |
{
"abstract": " In the present work, we explore the potential of spin-orbit (SO) coupled\nBose-Einstein condensates to support multi-component solitonic states in the\nform of dark-bright (DB) solitons. In the case where Raman linear coupling\nbetween components is absent, we use a multiscale expansion method to reduce\nthe model to the integrable Mel'nikov system. The soliton solutions of the\nlatter allow us to reconstruct approximate traveling DB solitons for the\nreduced SO coupled system. For small values of the formal perturbation\nparameter, the resulting waveforms propagate undistorted, while for large\nvalues thereof, they shed some dispersive radiation, and subsequently distill\ninto a robust propagating structure. After quantifying the relevant radiation\neffect, we also study the dynamics of DB solitons in a parabolic trap,\nexploring how their oscillation frequency varies as a function of the bright\ncomponent mass and the Raman laser wavenumber.\n",
"title": "Traveling dark-bright solitons in a reduced spin-orbit coupled system: application to Bose-Einstein condensates"
}
| null | null | null | null | true | null |
4594
| null |
Default
| null | null |
null |
{
"abstract": " This paper revisit and extend the interesting case of bounds on the Q-factor\nfor a given directivity for a small antenna of arbitrary shape. A higher\ndirectivity in a small antenna is closely connected with a narrow impedance\nbandwidth. The relation between bandwidth and a desired directivity is still\nnot fully understood, not even for small antennas. Initial investigations in\nthis direction has related the radius of a circumscribing sphere to the\ndirectivity, and bounds on the Q-factor has also been derived for a partial\ndirectivity in a given direction. In this paper we derive lower bounds on the\nQ-factor for a total desired directivity for an arbitrarily shaped antenna in a\ngiven direction as a convex problem using semi-definite relaxation techniques\n(SDR). We also show that the relaxed solution is also a solution of the\noriginal problem of determining the lower Q-factor bound for a total desired\ndirectivity.\nSDR can also be used to relax a class of other interesting non-convex\nconstraints in antenna optimization such as tuning, losses, front-to-back\nratio. We compare two different new methods to determine the lowest Q-factor\nfor arbitrary shaped antennas for a given total directivity. We also compare\nour results with full EM-simulations of a parasitic element antenna with high\ndirectivity.\n",
"title": "On methods to determine bounds on the Q-factor for a given directivity"
}
| null | null | null | null | true | null |
4595
| null |
Default
| null | null |
null |
{
"abstract": " Band gap tuning in two-dimensional transitional metal dichalcogenides (TMDs)\nis crucial in fabricating new optoelectronic devices. High resolution\nphotoluminescence (PL) microscopy is needed for accurate band gap\ncharacterization. We performed tip-enhanced photoluminescence (TEPL)\nmeasurements of monolayer MoSe2 with nanoscale spatial resolution, providing an\nimproved characterization of the band gap correlated with the topography\ncompared with the conventional far field spectroscopy. We also observed PL\nshifts at the edges and investigated the spatial dependence of the TEPL\nenhancement factors.\n",
"title": "Nano-optical imaging of monolayer MoSe2 using tip-enhanced photoluminescence"
}
| null | null |
[
"Physics"
] | null | true | null |
4596
| null |
Validated
| null | null |
null |
{
"abstract": " The defect in diamond formed by a vacancy surrounded by three\nnearest-neighbor nitrogen atoms and one carbon atom,\n$\\mathrm{N}_{3}\\mathrm{V}$, is found in $\\approx98\\%$ of natural diamonds.\nDespite $\\mathrm{N}_{3}\\mathrm{V}^{0}$ being the earliest electron paramagnetic\nresonance spectrum observed in diamond, to date no satisfactory simulation of\nthe spectrum for an arbitrary magnetic field direction has been produced due to\nits complexity. In this work, $\\mathrm{N}_{3}\\mathrm{V}^{0}$ is identified in\n$^{15}\\mathrm{N}$-doped synthetic diamond following irradiation and annealing.\nThe $\\mathrm{^{15}N}_{3}\\mathrm{V}^{0}$ spin Hamiltonian parameters are revised\nand used to refine the parameters for $\\mathrm{^{14}N}_{3}\\mathrm{V}^{0}$,\nenabling the latter to be accurately simulated and fitted for an arbitrary\nmagnetic field direction. Study of $\\mathrm{^{15}N}_{3}\\mathrm{V}^{0}$ under\nexcitation with green light indicates charge transfer between\n$\\mathrm{N}_{3}\\mathrm{V}$ and $\\mathrm{N_s}$. It is argued that this charge\ntransfer is facilitated by direct ionization of $\\mathrm{N}_{3}\\mathrm{V}^{-}$,\nan as-yet unobserved charge state of $\\mathrm{N}_{3}\\mathrm{V}$.\n",
"title": "Electron paramagnetic resonance and photochromism of $\\mathrm{N}_{3}\\mathrm{V}^{0}$ in diamond"
}
| null | null | null | null | true | null |
4597
| null |
Default
| null | null |
null |
{
"abstract": " Kisin and Pappas constructed integral models of Hodge-type Shimura varieties\nwith parahoric level structure at $p>2$, such that the formal neighbourhood of\na mod~$p$ point can be interpreted as a deformation space of $p$-divisible\ngroup with some Tate cycles (generalising Faltings' construction). In this\npaper, we study the central leaf and the closed Newton stratum in the formal\nneighbourhoods of mod~$p$ points of Kisin-Pappas integral models with parahoric\nlevel structure; namely, we obtain the dimension of central leaves and the\nalmost product structure of Newton strata. In the case of hyperspecial level\nstrucure (i.e., in the good reduction case), our main results were already\nobtained by Hamacher, and the result of this paper holds for ramified groups as\nwell.\n",
"title": "On central leaves of Hodge-type Shimura varieties with parahoric level structure"
}
| null | null | null | null | true | null |
4598
| null |
Default
| null | null |
null |
{
"abstract": " This paper gives a new flavor of what Peter Jagers and his co-authors call\n`the path to extinction'. In a neutral population with constant size $N$, we\nassume that each individual at time $0$ carries a distinct type, or allele. We\nconsider the joint dynamics of these $N$ alleles, for example the dynamics of\ntheir respective frequencies and more plainly the nonincreasing process\ncounting the number of alleles remaining by time $t$. We call this process the\nextinction process. We show that in the Moran model, the extinction process is\ndistributed as the process counting (in backward time) the number of common\nancestors to the whole population, also known as the block counting process of\nthe $N$-Kingman coalescent. Stimulated by this result, we investigate: (1)\nwhether it extends to an identity between the frequencies of blocks in the\nKingman coalescent and the frequencies of alleles in the extinction process,\nboth evaluated at jump times; (2) whether it extends to the general case of\n$\\Lambda$-Fleming-Viot processes.\n",
"title": "The sequential loss of allelic diversity"
}
| null | null | null | null | true | null |
4599
| null |
Default
| null | null |
null |
{
"abstract": " Most brain-computer interfaces (BCIs) based on functional near-infrared\nspectroscopy (fNIRS) require that users perform mental tasks such as motor\nimagery, mental arithmetic, or music imagery to convey a message or to answer\nsimple yes or no questions. These cognitive tasks usually have no direct\nassociation with the communicative intent, which makes them difficult for users\nto perform. In this paper, a 3-class intuitive BCI is presented which enables\nusers to directly answer yes or no questions by covertly rehearsing the word\n'yes' or 'no' for 15 s. The BCI also admits an equivalent duration of\nunconstrained rest which constitutes the third discernable task. Twelve\nparticipants each completed one offline block and six online blocks over the\ncourse of 2 sessions. The mean value of the change in oxygenated hemoglobin\nconcentration during a trial was calculated for each channel and used to train\na regularized linear discriminant analysis (RLDA) classifier. By the final\nonline block, 9 out of 12 participants were performing above chance (p<0.001),\nwith a 3-class accuracy of 83.8+9.4%. Even when considering all participants,\nthe average online 3-class accuracy over the last 3 blocks was 64.1+20.6%, with\nonly 3 participants scoring below chance (p<0.001). For most participants,\nchannels in the left temporal and temporoparietal cortex provided the most\ndiscriminative information. To our knowledge, this is the first report of an\nonline fNIRS 3-class imagined speech BCI. Our findings suggest that imagined\nspeech can be used as a reliable activation task for selected users for the\ndevelopment of more intuitive BCIs for communication.\n",
"title": "Online classification of imagined speech using functional near-infrared spectroscopy signals"
}
| null | null |
[
"Quantitative Biology"
] | null | true | null |
4600
| null |
Validated
| null | null |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.